Animation may be used to display a moving object, such as a person, a car, or a ball. Animation can be created and edited in software using various animation applications. A typical animation includes a plurality of frames. Each frame depicts an object comprised of a set of paths that define enclosed regions. Each region may be filled with an attribute, such as color. Between frames, the object, and therefore a region corresponding to the object, may move. Typically, a user manually colors each region in each frame in order to ensure that an object retains the same color between frames. Onion skinning is a method that may be used to assist the user in manually coloring regions across frames. In onion skinning, multiple frames are overlaid, so that the user can color regions in multiple frames at once. However, even with onion skinning, each region still needs to be manually colored by the user. The user has to manually inspect overlapping regions across frames and determine whether they correspond before coloring them. In addition, onion skinning is less useful when an object is moving quickly, and there is little or no overlap of corresponding regions between frames. An improved method of coloring regions across frames is needed.